Discovery of Five Probable Novae in M81

ATel #5489; K. Hornoch (Astronomical Institute, Ondrejov, Czech Republic), O. Vaduvescu, L. Dominguez, J. McCormac, T. Mocnik (ING, La Palma, Spain), Y. Ramanjooloo (ING, La Palma, Spain and University College London, UK), N. Gentile Fusillo (ING, La Palma, Spain and University of Warwick, UK), S. Doostmohammadi (ING, La Palma, Spain and Shahid Bahonar University, Iran)
on 20 Oct 2013; 22:58 UT
Credential Certification: Allen W. Shafter (aws@nova.sdsu.edu)

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We report the discovery of five probable novae in M81 on co-added 1600-s narrow-band H-alpha CCD images taken with the 2.5-m Isaac Newton Telescope (INT) + WFC at La Palma under ~1.6" and ~1.4" seeing on 2013 Oct. 15.175 UT and 16.219 UT, respectively. The new objects are well visible on the co-added images (see the finding chart linked below), but are not present on numerous narrow-band H-alpha archival images from the INT down to limiting magnitude as faint as H-alpha = 22.3. We obtained also Sloan r'-band images which helped us to classify the objects. Strong H-alpha emission together with relative faintness in Sloan r' band supports the classification of the objects as novae.

Designations, positions, and offsets of the new objects from the M81 center are summarized in the following table:

 
  TOCP designation    CBAT designation  R.A. (J2000)  Dec. (J2000)  Offset R.A.  Offset Dec. 
 
PNV J09551435+6903060  M81N 2013-10a?   09 55 14.35   +69 03 06.0    100.9" W      49.1" S 
PNV J09551789+6905455  M81N 2013-10b?   09 55 17.89   +69 05 45.5     81.9" W     110.4" N 
PNV J09552718+6904083  M81N 2013-10c?   09 55 27.18   +69 04 08.3     32.1" W      13.2" N 
PNV J09553551+6906468  M81N 2013-10d?   09 55 35.51   +69 06 46.8     12.5" E     171.7" N 
PNV J09554863+6904143  M81N 2013-10e?   09 55 48.63   +69 04 14.3     82.8" E      19.2" N 
 

The photometry obtained with the INT + WFC is summarized here:

 
 
                        2013 10 15.175    2013 10 15.195    2013 10 16.219    2013 10 16.219 
 
       Object             H-alpha mag      Sloan r' mag       H-alpha mag      Sloan r' mag 
 
PNV J09551435+6903060    20.0 +/- 0.25     22.5 +/- 0.35     20.1 +/- 0.2      22.4 +/- 0.3 
PNV J09551789+6905455    19.7 +/- 0.2      21.2 +/- 0.2      19.8 +/- 0.2      21.3 +/- 0.2 
PNV J09552718+6904083    19.6 +/- 0.2         > 21.8         19.6 +/- 0.2         > 21.9 
PNV J09553551+6906468    19.9 +/- 0.25        > 22.3         20.0 +/- 0.2         > 22.5 
PNV J09554863+6904143    19.6 +/- 0.15     21.3 +/- 0.25     19.5 +/- 0.15     21.4 +/- 0.2 
 

This work is based on observations made with the Isaac Newton Telescope operated on the island of La Palma by the ING in the Spanish Observatorio del Roque de los Muchachos.

Finding chart